Process of and apparatus for polishing explosive powder.



I F. 1.- nu FONT. PROCESS OF AND APPARATUS FOR POLISHING EXPLOSIVEPOWDER.

APPLICATION FILED JULY 28,1915.

Patented Sept. 4, 1 917.

4 of the powder,

orrrcn IEEi-ANSIS I. no POINT, OF WILMENG-TDN, IDELAVTARE, ASSIGNOR, BYDIRECT AND MESNE HTS, T9 BALL GRAIN EXELQSZVES COMPAQ (Y,

EATIQN OE KYEL' WARE.

GE 'WILMINGTON, DELA- Pa tentcd'Sept, 4:, 1 391? Application filed July23, 1915. Eerie Ho, $2,266.

To aZZ whom it may concern:

Be it known that l, l ner-tors l. DU Pour, a "zen 0r United States,residing iington, county of cw Castle, and of Delaware, have invented anew and improvement in Processes of and atus 0: Polishing ExplosivePowder, hich the following is a lull, clear, and exact description,reference being had to the adrzompanying drawings, which form a part of.this specification.

The object of my invention is to polish or use explosive granularpowder. In the finer-y process or" glazing powder, a large yabout one totwo tonsis placed arr-cl three to four feet in diter and from six toeight feet in length barrel is filled from one-half to tworzs full andis rotated on its axis at such L ced that the grains of powder slideover nether until they are sutliciently ieced and. polished. Theoperation is the powder is glazed,

d until at.

' operation is attended with "ger and not infrequently c. plosionsoccur, Such explosions invariioly result in the total destruction of themill mdin the loss of the lives of any w orlo men r 0 may be on thepremises at the time oi the explosion. No matter how carefully theoperation is conducted, the danger of. era plosion remains. Y Instead ofattempting primarily to remove or diminish the danger of the ignition.

to which efforts have hitherto been directed, my invention contemplatesdiminishing the destructive effects of the em plosion to such an extentthat, in the event or explosion, there will be practically no 1.3 angerof injury either to the operatives or to the machinery. My inventionalso conplatcs effecting this result while at the same time renderingthe operation continuous and more nearly completely automatic andwithout reduction or output or sacrifice of efiiciency but on thecontrary with an actual increase in both these factors.

it is apparent that when a large amount oi powder is in the form of acompact and confined In its ignition necessarily producs as vi ntexplosion, whereas if the same quantity of powder were spread out overgreat area or strung out in a long line, ignition would cause to burnrather than to explode with force, thereby immensely reducing itsdestructive effects. However, it is impracticable to thus distribute andmechanically handle, at any given time, a volume of powder that would becontained in a barrel six to eight feet long and three to four feet indiameter, while if a substantially smaller quantity were handled, theoperation would not be feasible commercially.

in my invention 1 accomplish the results sought, without sacrifice ofany essential factor, by so distributing and handling the powder that atany given time only a comparatively small quantity or": powder isundereoing the polishing operation, while this smaller quantity ofpowder is so widely distributed that in the event of explosion no damagewill result except practically negligible damage to the powdercontainer, At the same time the speed of the operation is in inverseproportion to the quantity of powder at any given time undergoing treat:

inent, thereby causing no decrease in output. Additionally, provision ismade so that the operation may be conducted continuously instead ofintermittently, thereby increasing the output, reducing labor, anddiminishing the chances of accidental ignition.

The invention may be best explained by first referring to theaccompanying drawings, in which Figure l is a cross-sectionaldiagrammatie view of my improved apparatus for carrying out my improvedprocess Fig. 2 isa longitudinal sectional view of the same.

In place of the usual barrel l provide a tube which, :t'or example, maybe eight inches in diameter and thirty-two feet long. The iube isrevolved as on rolls n. A feed chute 0 delivers into an opening in oneend of the tube and at this end there is a short section oi a spiral f,fixed in the-tube and flaring in the direction to start the materialmoving toward the other end of the tube. A free space at s 's leftbetween the spiral and the flange at the end of tlic'tube, into whichspace the material is fed, and even though the level at this point islow, the efiect of the spiral is to fill the tube continuously to asmuch higher level as may be desired. This level is regulated by thediameter of the hole 6 at the delivery end of the tube. Thushycontinuously supplying explosive powder through the feed chute o andrevolving tube m at a certain speechtlie niaterial gradually fed alongthroughout the length of the tube and overflows out of the opening a,maintaining; an active polishing or glazing zone the full length'olthetube.

1 hove discovered that, in any polishing barrel, the powder actuallybeing upon given time is not "he'entire mass of \vder in the barrel butonlyla comparatively thin Thus, Fig. 1 represents the actior thematerial in polishing is rotating; in the direction of the arrow. hematerial climbs up the side of e barrel and when the particles havereached a point well up toward the top, they tumble down the exposedface. it is only in this tumbling down operation that the .ins rub orslide upon one another and lQCQll a po h, and it is only in the cinparat vel y thin zone represented at that this operation occurs. Thusthe amount of powder being glazed at any given time depends upon thearea of the active zone {assuming a given speed of movement of thegrains} and not upon the hull; of powder in the container.

For example, it may readily be calculated that barrel 6 feet long and lfeet in diameter will contain six times as much powder a tube 8 inchesin diameter and 361i'eet long, bu the area of the active zone, assum ingthat botn containers are half full, will be as great in the tube ofsmall capacity as in the barrel of large capacity. if, therefore, thetube is rotated at such greater angular speed than the barrel as toimpart to the individual grains the same desirable speed of travel as inthe barrel, it is clear that, at a given time, much powder is beingglazed in the tube as in the barrel and that the entire contents of thetube will be glazed in one-sixth the time required to glaze the entirecontents of he barrel.

It will thus be seen that within any given time the output of myimproved polishing apparatus will be as great as the output of theordinary glazing barrel, assuming no loss of time in filling anddischarging the barrel. in fact, liowe xer, this loss of time is not anegligible factor and therefore the output of my improved apparatus mayactually be increased, if desired, over that of the ordinary polishingbarrel, while at any given 55 time a very much smaller quantity ofpowder is being glazed nd the same is so widely distributed that, in theevent of ignition, it will burn like a fuse rather than explode like aconfined charge. Indeed, actual experience shows that the only efiect isto spread apart the staves oi'the tube to allow the flame to escape,and, aside from the charring of the wood were by the burning powder, themachinery "of the mill is not injured barrel, which l hile, therefore,it is essential to invention that the long h of the powder mass be greatrole vely to its depth, while it is the tube is half filled, such tialfactor is, therefore, the relation between length and depth of powderniass. Experiment has shown that, in the event of ignition oi? thepowder, burning with flame, as disiguished from explosionwithdestructive force, cannot be assured, in a commercial plant, unless theratio between length and deph of powder mass is at least ll to l, with amaximum depth of eight inches of powder mass; or, in the event that thetube is about half -filled, its diameter must not exceed 16 inches,while the ratio between its length and radius should be at least will bunderstood that the substitution e of te elo. gated tube of relativelysmall capacity having comparatively rapid an, ;u-

of rotation for the compact bar will be understood that the invention isapplicable either to the smoot iening' of powder preparatory to finalglazing with graphite or other polishing material, or to the finalglazing; after the smoothening operation.

Having now fully described my invention, what I claim-and desire toprotect by Letters Patent is:

1. The process of polishing explosive granular powder which consists indistributing the powder longitudinally to form an elongated. string,iinpartirg to'the powder a movement of rotation on an axis parallel toits forward progressing movement, applying a forward propulsion forcedirectly to the powder throughout only a relatively small part ofitslength and restricting the advance of the powder at the far end ofthe string to regulate and maintain its depth.

'2. The process of polishing explosive granular powder which consists indistribthe str' and. throughout a relatively short messes length of thestring, impar ing to the powder a movement of rotat on on an axisparallel to its forward progressive movement while eliminating allchstruction to the free rolling of the grains one upon another, and

regulating the depth of the string indestring, imparting to the powder amove ment of rotation on an axis parallel to its forward progressivemovement while elnninating all obstruction to the free rolling of thegrams oneupon another, and restricting the advance of the powder at theother end of the string to regulate its depth.

4. The process of polishing explosive granular powder which consists indistributing the powder longitudinally to form a string having a lengthnot less than approximately fourteen times its maximum depth, impartingto the powder a turning move-- ment on an axis parallel to itslongitudinal y direction of extension, and controlling the desired depthby restricting its longitudinal flow.

5. In an apparatus for polishing explosive powder, the combination witha tube of comparatively great length and small diameter,

its interior, throughout the greater part of its length, being open andfree of obstruction to tumbling of the powder, of means to feed thepowder into one end of the tube, and means occupying a relatively shortpart of the length of the tube to insure the forward travel of thepowder within the tube.

6. In an apparatus for polishing explosive powder, the combination witha tube of comparatively great length and small diameter, of means torotate the tube, feeding means to introduce the powder at one endthereof, and means within the tube and occupying a relatively short partof its length and positioned at the inlet end thereof to start thepowder through the tube. a

7 In an apparatus for polishing explosive powder, the combination withan elongated rotary tube, of feeding meanr to introduce the powder atone end, propulsion means occupying only a relatively short part of thelength of the tube to effect the propulsic-'11 of the powder toward thedischarge end, and means controlling the discharge and determining thedepth of the material in the tube.

8. In an apparatus for polishing explosive powder, the combination witha tube of cone paratively great length and small diameter, of means torotate'the tube, feeding means to introduce the powder at one endthereof,

propulsion means occupying a relatively short part of the length of thetube-and pesitioned at the inlet end thereof, and means at the dischargeend of the tuloe to regulate the depth of powder therein 9. In anapparatus for polishing explosive powder, the combination with anelongated rotary tube, of means to introduce the powder at one endthereof, a section of a spiral at the inlet end portion of the tube andturning therewith, the discharge end of the tube having a central holewhose diameter regulates the depth of powdr in he tube.

10. In an apparatus for polishing explosive owder, the combination withan elongated at its inlet end, of a hopper feeding into the inlet endthereof, and a section of a spiral fixed to the tube at its inlet endportion but spaced from the extreme inlet end, the dis charge end of thebeing conical and provided with a central. open FRANCES I. on FONT,

rotary tube, having a central opening

